[Next Page] [Contents] [Previous Page] [Exit]


A. General. Meteor rates can be obtained by individuals or groups. The American Meteor Society collects only those rates made by individual observers reporting hourly rates. Certain statistical treatment permits use of group counts but the AMS is not set up to process such information. While group observing does have certain social and logistic advantages, in reporting we must insist that each person report only what he or she sees, regardless of whether co-observers see the same meteor or not. We tacitly assume that observers in such circumstances are NOT actively communicating and commenting to each other while observing.

Meteor rates need to be corrected for less than perfect conditions, i.e. bright sky, clouds, haze, and ground obstruction. Further correction is needed if the observer is plotting or recording data by hand or both. The sky condition factor F is called 1.0 if stars to mag. 6.0 are visible at the zenith and if the sky is clear and free of obstruction. The factor F is lowered 0.1 for each 0.5-mag. loss in zenith star. If the sky is partly cloudy and/or partly obstructed, the observer must estimate roughly what percentage of his field of view is blocked. Estimates are made to the nearest 10%, then F is lowered 0.1 for each 10%. If only one side of the sky is cloudy, one can face the other side and obtain a higher value for F. If observing time was short of a full hour, then F is lowered 0.1 for each 6 minutes deficit. The minimum requirement for inclusion in past A.M.S. rate catalogs is F0.5. This minimum will likely be retained for future work.

B. Personal Factors. The human eye is a notoriously poor meteor detector. Whereas one observer might average a dozen or so meteors in an hour, the total number visible over the entire sky may be several hundred. The observer will generally see only those meteors appearing at or near his central vision, particularly the fainter ones. Even a group of observers will record only a small fraction of the meteors appearing.

There are a few individuals with unusual perception for meteors reporting three to five times the usual rate. Such observers see meteors over their entire field of view but would not be seeing many of them well.

Two observers working together will usually obtain different rates, even if they watch the same area of sky. Perception varies from one individual to the next. The ability to see very faint stars does not necessarily imply that high meteor rates follow. The eyes respond differently and rather poorly to fleeting phenomena.

Always present to some extent are flashes that may or may not be meteors. Some observers are influenced more thon others by this problem. In each case one must decide whether he did see a meteor. The ease of detection usuolly corresponds to how far from the center of vision the event occurred. Fireflies and intra-ocular flashes are common explanations for non-meteor events. Flashes can also be generated from bright stars by sudden head movement, particularly if glasses are worn. Movement should be restricted to eyes as much as possible, and then not too fast or too slow. Meteors not well seen that appear near bright stars should be considered with some suspicion. In some cases, flashes within the eye can be generated by cosmic rays. These are seen even when the eyes are closed.

Meteor rates are influenced by observer alertness. Obviously fatigue will cause one to miss meteors, especially if one cannot keep his eyes open. The ability to stay awake and maintain long periods of alertness during the night various with each individual. Some persons fatigue shortly after beginning work; others seem to begin slowly and reach a peak of alertness before declining again. A great oid for all observers is sleep immediately before observing, preferably an amount equal to the length of the observing period planned. Any sleep, however, is better than none at all.

[Next Page] [Contents] [Previous Page] [Exit]